The wiper apparatus generally includes a wiper arm, which is pivotable about a shaft, and a wiper blade, which is supported by the wiper arm and wipes, for example, a windshield. With this structure, the wiper blade moves arcuately with the wiper arm about the shaft and wipes a sectorial area of the windshield. When such a structure is employed, the length of the wiper blade needs to be increased to increase the wiping area wiped by the wiper blade. However, it is desired that the wiping area be increased without increasing the length of the wiper blade.
To respond to the demand, for example, the structure disclosed in Patent Document 1 is embodied. In the conventional structure, a four-link mechanism shown in FIGS. 8 to 10 is used as the operating mechanism of the wiper arm. As shown in FIG. 9, the four-link mechanism L includes four shafts 43, 44, 46, 47, which are parallel to one another. FIGS. 8 and 10 are diagrams viewed along the direction in which axes C1, C2, C3, C4 of the shafts 43, 44, 46, 47 extend. FIG. 9 is a diagram viewed along the direction perpendicular to the direction in which the axes C1, C2, C3, C4 extend. As shown in FIGS. 8 and 9, a pair of link levers 41, 42 is mounted on a mounting portion formed on a vehicle body such as a blackout section at the lower part of the windshield and a body panel of the vehicle below the windshield. The lower ends of the link levers 41, 42 are pivotably supported by the shafts 43, 44, respectively. The proximal end of a wiper arm 45 is coupled to the distal ends of the link levers 41, 42 via the shafts 46, 47. That is, the distal ends of the link levers 41, 42 are connected by the proximal end of the wiper arm 45. A wiper blade 48 is supported at the distal end of the wiper arm 45.
A first link L1 of the four-link mechanism L is formed at the above-mentioned mounting portion by the section between the shafts 43, 44. A second link L2 is formed by one of the pair of link levers 41, 42, that is, the first link lever 41 located away from the wiper blade 48. A third link L3 if formed by one of the pair of link levers 41, 42, that is, the second link lever 42 located close to the wiper blade 48. A fourth link L4 is formed by part of the wiper arm 45 located between the shafts 46, 47.
As shown in FIG. 9, a drive mechanism 49 including a motor (not shown) is connected to the shaft 43 supporting the first link lever 41. When the drive mechanism 49 causes the first link lever 41, in other words, the second link L2 of the four-link mechanism L to pivot back and forth about the shaft 43 within a predetermined range, the third link L3 and the fourth link L4 of the four-link mechanism L pivot in accordance with the pivoting motion of the second link L2. As a result, the wiper arm 45 pivots back and forth between a storage position shown in FIG. 8 and an upright position shown in FIG. 10, and thus the wiper blade 48 wipes the windshield. The pivoting motion of the wiper arm 45 is the combination of the pivoting motion of the entire wiper arm 45 about the shaft 46 and the pivoting motion of the proximal end of the wiper arm 45 coupled to the shaft 46 about the shaft 43. As a result, the area of the windshield wiped by the wiper blade 48 is increased.    Patent Document 1: Japanese National Phase Laid-Open Patent Publication 2006-514592